Pump impeller



United States Patent 3,156,190 PUMP IMPELLER Martin Stiihle, Hidrostal, Jiron Huaraz 951 Brena, Lima, Peru Filed Mar. 14, 1963, Ser. No. 265,131 2 Claims. (Cl. 10388) This invention relates to improvements in rotary pumps and is particularly directed to a pump having a novel form of impeller which contributes to efficient handling of mixtures of liquids and solids. Mushy, pulpy, pasty, or fibrous materials contained in water may be handled without clogging the parts of the pump.

This application is a continuation-in-part of my copending application, Serial No. 141,251, filed September 25, 1961, for Single-Blade Centrifugal Pump Impeller, now abondoned.

It is an important object of this invention to provide an improved pump assembly having a rotary impeller incorporating a spiral screw blade, the screw blade having an outer periphery defining a flaring surface of revolution, the blade having a pointed end offset from the rotary axis of the impeller, and shaped so that no central projection is provided in which solids may hang up or accumulate to cause clogging.

Another object is to provide a novel form of impeller for a rotary pump.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIGURE 1 is a sectional view showing a preferred embodiment of this invention;

FIGURE 2 is a front elevation taken substantially on the lines 2-2 as shown in FIGURE 1; and

FIGURE 3 is a sectional view showing a modification.

Referring to the drawings, the pump assembly generally designated includes a casing 11 and a rotary impeller 12. The casing 11 includes a chamber portion 13, having an outlet 14, and also includes a tapered inlet portion 15. The tapered inlet portion 15 has a flaring inlet bore 16, leading from a restricted inlet opening 17 to the volute chamber 18 in the casing 11. The inlet pipe 19 is flange connected to the small end of the taper portion 15 of the casing 11.

The impeller 12 is mounted to rotate on the casing 11 and is provided with a first flaring hub portion 21 concentrically mounted in said flaring inlet bore 16 and flaring in the same axial direction but having substantially lesser diameter. Said hub portion 21 extends into said volute outlet chamber 18. A second hub portion 26 merges with the first hub portion 21 and extends upstream and converges from the first hub portion. This second hub portion 26 has an axis 27 angularly oflset with respect to the axis of rotation of the first hub portion 21 and merges therewith so as to provide a continuous, smooth surface with said first hub portion 21. A single continuous spiral screw blade 22 is fixed to and encircles the surface of the first hub portion 21 and second hub portion 26 and has an outer periphery 23 defining a flaring surface indicated by the phantom lines 24. The screw blade 22 is of substantially constant thickness and smoothly merges with and covers the small end of the hub 21 and extends upstream into the tapered bore 16 beyond the end of the first hub portion 21. The

extending portion terminates in a leading end 25 offset from the rotary axis of the impeller. The leading end 25 is inclined to the rotary axis of the first hub portion 21. The surface of revolution 24 defined by rotation of the outer edge or periphery 23 is concentric with said flaring inlet bore 16 and is closely adjacent thereto. The clearance between the periphery 23 of the screw blade 22 and the conical bore 16 varies from minimum clearance at the leading end 25 to maximum clearance at the large end of the screw blade 22. The screw blade 22 has a root portion 28 engaging and merging into a smooth surface with said axially extending second hub portion 26, so that no abrupt shoulder is formed between said root portion 28 of the screw blade 22 and the surface of the offset second hub portion 26.

The diameter of the concentric inlet opening 17 is preferably less than the diameter of the circle traversed by the leading end 25, so that any solid material which passes through the inlet opening 17 with the liquid does not hang up or accumulate at any point on the impeller, but, on the contrary, is carried along between convolutions of the screw blade 22 into the volute chamber 18 and out through the outlet 14.

The small end of the first hub portion 21 is shown in phantom lines 21a, but in reality there is no central point at the apex of the hub because it is covered by and merged with the second hub portion 26.

While the bore 16 and the surface revolution 24 have both been shown in FIGURE 1 as being conical, it is to be understood that these surfaces need not be strictly conical, but may be curved in cross section to form a flaring bore and a flaring surface of revolution. The hub 21 may be similarly curved.

In a modified form of the device shown in FIGURE 3, a flaring or conical sleeve 30 forms a part of the impeller 12a and is fixed to the outer periphery 23a of the spiral screw blade 22a. A spiral passage 31 is thus formed between the tapered sleeve 3%) and the screw blade 22a.

This passage 31 extends from the small end of the impeller 12a to the volute chamber 18a. In other respects, the device of FIGURE 3 is similar to that described above.

Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth, but that my invention is of the full scope of the appended claims.

I claim:

1. In a pump, the combination of a casing having a volute outlet chamber and a flaring inlet bore defined by a surface of revolution, the large end of said flaring inlet bore opening into said volute outlet chamber, an impeller mounted to rotate within said flaring inlet bore, said impeller having a first flaring hub portion concentrically mounted in said flaring inlet bore and flaring in the same axial direction but having a substantial lesser diameter and extending into said volute outlet chamber, a second offset hub portion merging with the first hub portion and extending upstream and converging from the first hub portion and having an axis angularly oflset with respect to the axis of the first hub portion, and merging therewith so as to provide a smooth continuous sur face with said first flaring hub portion, a single continuous spiral screw blade of substantially constant thickness encircling said first and second hub portions and extending axially upstream from said second oifset hub portion, said screw blade having a leading end inclined to said axis of said first hub portion and said screw blade having an outer edge that on the rotation thereof said edge defines a surface of revolution concentric with said flaring inlet bore and closely adjacent thereto, and said screw blade having a root portion engaging and merging into a smooth surface with said offset axially extending second hub portion so that no abrupt shoulder is formed between said root portion of the screw blade and the surface of said offset second portion of the hub.

2. The combination set forth in claim 1 in which a flaring sleeve is fixed on the outer periphery of the screw blade to enclose it within the flaring inlet bore.

References Cited in the file of this patent UNITED STATES PATENTS Schetzel Sept. 13, Hutchinson Aug. 18, Chapman Feb. 8, Hanna Dec. 3, Schmidt Sept. 17, Nickerson July 28, Geske Jan. 1,

FOREIGN PATENTS Austria Oct. 25, Great Britain Jan. 25, France Apr. 29,

Germany Nov. 26, 

1. IN A PUMP, THE COMBINATION OF A CASING HAVING A VOLUTE OUTLET CHAMBER AND A FLARING INLET BORE DEFINED BY A SURFACE OF REVOLUTION, THE LARGE END OF SAID FLARING INLET BORE OPENING INTO SAID VOLUTE OUTLET CHAMBER, AN IMPELLER MOUNTED TO ROTATE WITHIN SAID FLARING INLET BORE, SAID IMPELLER HAVING A FIRST FLARING HUB PORTION CONCENTRICALLY MOUNTED IN SAID FLARING INLET BORE AND FLARING IN THE SAME AXIAL DIRECTION BUT HAVING A SUBSTANTIAL LESSER DIAMETER AND EXTENDING INTO SAID VOLUTE OUTLET CHAMBER, A SECOND OFFSET HUB PORTION MERGING WITH THE FIRST HUB PORTION AND EXTENDING UPSTREAM AND CONVERGING FROM THE FIRST HUB PORTION AND HAVING AN AXIS ANGULARLY OFFSET WITH RESPECT TO THE AXIS OF THE FIRST HUB PORTION, AND MERGING THEREWITH SO AS TO PROVIDE A SMOOTH CONTINUOUS SURFACE WITH SAID FIRST FLARING HUB PORTION, A SINGLE CONTINUOUS SPIRAL SCREW BLADE OF SUBSTANTIALLY CONSTANT THICKNESS ENCIRCLING SAID FIRST AND SECOND HUB PORTIONS AND EXTENDING AXIALLY UPSTREAM FROM SAID SECOND OFFSET HUB PORTION, SAID SCREW BLADE HAVING A LEADING END INCLINED TO SAID AXIS OF SAID FIRST HUB PORTION AND SAID SCREW BLADE HAVING AN OUTER EDGE THAT ON THE ROTATION THEREOF SAID EDGE DEFINES A SURFACE OF REVOLUTION CONCENTRIC WITH SAID FLARING INLET BORE AND CLOSELY ADJACENT THERETO, AND SAID SCREW BLADE HAVING A ROOT PORTION ENGAGING AND MERGING INTO A SMOOTH SURFACE WITH SAID OFFSET AXIALLY EXTENDING SECOND HUB PORTION SO THAT NO ABRUPT SHOULDER IS FORMED BETWEEN SAID ROOT PORTION OF THE SCREW BLADE AND THE SURFACE OF SAID OFFSET SECOND PORTION OF THE HUB. 